基于SSR标记的花生品种遗传多样性分析

从212对SSR标记引物中筛选出48对引物,对63份花生品种进行遗传多样性分析,共得到251个等位变异,变异范围为2~13个,平均每个标记位点有5.23个变异;48个SSR标记的多态性信息含量为0.252~0.873,平均为0.647;63份材料的遗传多样性指数为0.508~2.243,平均值为1.272;品种间的遗传相似系数在0.657~0.960之间,不同类型的花生品种间的遗传相似性较小,不同来源花生品种间的亲缘关系也较远;聚类分析结果表明,63个花生品种在遗传相似系数为0.74处分为4大类,聚类分析结果与传统的花生分类结果吻合。     

Isolation and characterization of natural Ara h 6: evidence for a further peanut allergen with putative clinical relevance based on resistance to pepsin digestion and heat

Peanut allergy is a significant health problem because of its prevalence and the potential severity of the allergic reaction. The characterization of peanut allergens is crucial to the understanding of the mechanism of peanut allergy. Recently, we described cloning of the peanut allergen Ara h 6. The aim of this study was isolation and further characterization of nAra h 6. We purified nAra h 6 from crude peanut extract using gel filtration and anion exchange chromatography. The preparation was further characterized by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) with subsequent immunoblotting. Stability of nAra h 6 was studied by an in vitro digestibility assay as well as by resistance against thermal processing. Sequencing of nAra h 6 identified the N-terminal amino acid sequence as MRRERGRQGDSSS. Further results clearly demonstrated stability of nAra h 6 against pepsin digestion and heating. Immunoglobulin G (IgE) binding analysis and its biological activity shown by RBL 25/30-test of natural Ara h 6 supported the importance of this peanut allergen. Investigation of nAra h 6 revealed evidence for a further peanut allergen with putative clinical relevance based on resistance to pepsin digestion and heat.     

Effect of denaturation during extraction on the conformational and functional properties of peanut protein isolate

Peanut protein isolate (PPI) was extracted by alkali dissolution and acid precipitation from defatted peanut flour. The effects of extraction conditions on the denaturation and functional properties of PPI were investigated. In comparison with native peanut protein (NPP) which was extracted by ammonium sulfate, the PPI extracted by alkali dissolution and acid precipitation had a higher extent of denaturation. Arachin was affected more easily by the extraction process than conarachin and led to a noticeable decrease of thermal stability of PPI. PPI contained much lower sulfhydryl and disulfide bond contents than NPP. The analyses of intrinsic fluorescence spectra indicated a more compacted tertiary conformation of NPP than PPI. Extraction process influenced the functional properties of PPI, such as protein solubility, emulsifying activity index and foaming capacity. The relatively poor functional properties of PPI might be associated with protein denaturation/unfolding and subsequent protein aggregation.

Industrial relevance

Peanut is an important oilseed crop and a well-accepted food. After oil production through thermal treatment, the defatted peanut flour is the main byproduct, which possesses a large amount of proteins. However, due to the low extraction yield and poor functional properties of these proteins, they are not well utilised in industry till now. In this work, peanut proteins were extracted by two techniques. The results indicated that extraction technique could significantly modify the functional properties of peanut proteins. Therefore, this work is helpful for industrial utilisation of peanut proteins.     

流式细胞仪检测铝胁迫诱导的花生悬浮细胞程序性死亡

以耐铝品种99-1507和铝敏感品种中花2号为材料,应用荧光显微镜和流式细胞仪研究铝对悬浮细胞活性及其线粒体生理的影响,并检测悬浮细胞程序性死亡率。结果表明：铝处理12h后,随着铝浓度增加,悬浮细胞FDA（Fluorescein diacetate）荧光信号逐渐减弱,PI（Propidium Iodide）荧光信号增强,细胞活性下降;线粒体超氧阴离子含量和H202含量随着铝浓度的增加逐渐上升;线粒体膜电位（△ψm）随着铝浓度增加逐渐下降,中花2号下降幅度大于99-1507。501μmol／L及其以上浓度的铝可以显著诱导花生悬浮细胞程序性死亡,铝浓度越高死亡细胞数量越多,同等浓度铝处理下中花2号细胞死亡率高于99-1507,差异达到显著水平。应用流式细胞仪能够准确地检测悬浮细胞程序性死亡的发生情况,细胞程序性死亡率与花生品种的耐铝性呈负相关关系。     

Enzymatic hydrolysis and their effects on conformational and functional properties of peanut protein isolate

The effects of limited enzymatic hydrolysis by Alcalase on the conformational and functional properties of peanut (Arachis hypogaea L.) protein isolate (PPI) were investigated. Acid subunits of arachin were most susceptible to Alcalase hydrolysis, followed by conarachin and the basic subunits of arachin. Enzymatic hydrolysis increased the thermal stability of arachin and led to a sharp increase in the number of disulphide bonds with a decrease of the sulphydryl group in PPI hydrolysates in comparison with PPI. The analysis of intrinsic fluorescence spectra indicated a more moveable tertiary conformation of PPI hydrolysates than PPI. The limited emzymatic hydrolysis improved the functional properties of PPI, such as protein solubility and gel-forming ability, but impaired the emulsifying activity index.     

Optimizing microencapsulation of peanut sprout extract by response surface methodology

This study was carried out to optimize conditions for peanut sprout extract microencapsulation by response surface methodology (RSM). The coating materials of microencapsulation were medium-chain triacylglycerol (MCT) for primary emulsion, and whey protein concentrates (WPC), maltodextrin (MD) and gum Arabic (AG) for secondary emulsion. The yield of microencapsulation of peanut sprout extract was investigated with respect to four variables (ratio of core and coating materials, concentration of primary emulsifier, ratio of W/O emulsion and secondary coating materials and concentration of secondary emulsifier) in RSM. The optimal conditions for microencapsulation of peanut sprout extract were 1:2 as the ratio of core material to coating material, 1.25% (w/v) of primary emulsifier concentration, 1:1.23 as W/O emulsion to secondary coating material, 1.21% (w/v) as secondary emulsifier concentration and 30% (w/w) as WPC concentration for spray drying. In conclusion, the microencapsulation of peanut sprout extract under the optimized conditions by RSM ensures the smaller size (3–7 μm) of microcapsules with the highest yield reaching to 98.74%.     

酶法处理对花生水剂法制油的影响

在花生水剂法制油工艺中,利用以纤维素酶为主体包含果胶酶的复合酶系处理碾磨后的油料能显著提高花生油收率及花生蛋白得率。经研究得出酶处理的最适参数范围如下：加酶量０ ．２ ％ ～０ ．３ ％ ,酶反应时间４ｈ ,ｐＨ６ ～７ ,温度４０ ～５０ ℃。     

Removing peanut allergens by tannic acid

Tannic acid (TA) forms insoluble complexes with proteins. The aims here were to remove major peanut allergens as insoluble TA complexes and determine if they would dissociate and release the allergens at pH 2 and 8 (gut pH). Release of the allergens in the gut could lead to absorption and consequently an allergic reaction. TA (0.25, 0.5, 1, and 2 mg/ml) was added to a peanut butter extract (5 mg/ml; pH 7.2), stirred, and centrifuged. The precipitates were then suspended in buffer at pH 2, centrifuged, re-suspended at pH 8, and centrifuged. Supernatants from each step were analysed by SDS–PAGE, ELISA, and Western blots. The effect of NaCl (1 M) on complexes was also determined. Results showed that complexes formed at a TA concentration >0.5 mg/ml did not release major peanut allergens at pH 2 and 8, regardless of 1 M NaCl being present or not. IgE binding of the extracts was reduced substantially, especially at a TA concentration of 1–2 mg/ml. Animal or clinical studies are still needed before TA can find an application in the development of low-allergen peanut products/beverages or the removal of peanut allergens due to accidental ingestion.     

Effect of some operating variables on the microstructure and physical properties of a novel Kefir formulation

In this work, the rheological and textural properties, water-holding capacity (WHC), syneresis, and microstructure of a novel formulation of Kefir were studied by varying the incubation time and temperature, as well as the ratio of peanut-milk and skimmed-milk. Generally, all the experimental responses resulted to be significantly affected (p < 0.05) by all dependent variables examined. Kefir WHC was not significantly influenced (p > 0.05) by the fermentation temperature.     

Biosensors for monitoring the isothermal breakdown kinetics of peanut oil heated at 180 °C. Comparison with results obtained for extra virgin olive oil

The present research was devoted to studying the kinetics of the artificial rancidification of peanut oil (PO) when a sample of this oil was isothermally heated at 180 °C in an air stream. The formation of radical species due to heating was evaluated using a radical index whose value was determined using a biosensor method based on a superoxide dismutase (SOD), while the increasing toxicity was monitored using a suitable toxicity measuring probe based on the Clark electrode and immobilized yeast cells.